Sleep is one of the few remaining physiological phenomena that have systemic effects for which underlying molecular mechanisms are not known. While many important theories have been raised about its restorative function and, in recent years, its role in memory consolidation, no theory fully explains what might trigger sleep or waking. The overall goal of this work is to determine how sleep is regulated on a cellular and molecular level. Recent efforts by different labs have opened up the field of Drosophila genetics allowing for detailed analysis of sleep. Similar to mammals, Drosophila have an increased arousal threshold during sleep, show stereotypic rest positions and show rebound sleep following a period of deprivation. But Drosophila offer distinct advantages over mammals in research. They have a short regeneration time, genetic tractability and spatial and temporal control over transgenic expression. By using Drosophila to study the anatomical areas, cell populations and cellular pathways involved, we have the unprecedented opportunity to understand how and why animals need to sleep. Preliminary data indicate that sleep regulation can be mapped to specific loci in the Drosophila brain, in particular to the mushroom body (MB). We propose to identify the neurochemical basis of this regulation and refine the anatomical subdivisions that regulate sleep within the mushroom body. We hypothesize that sleep is regulated by specific neurochemicals acting in distinct regions of the MB. In order to address this hypothesis we plan to identia mushroom body specific octopamine receptor, two dopamine receptors and the serotonin 5HT-1a receptor. We also plan to examine the effects of modulating inputs, including dopamine, serotonin, and octopamine into the mushroom body. These studies will identify specific cells and molecules that regulate sleep in Drosophila. It is expected that at least some of these underlying mechanisms will be conserved in mammals, and will provide insight into the regulation and perhaps the function, of sleep.